chapter  12
104 Pages

Fundamentals of Vibrations and Acoustic Noise

ByJames Weisheng Jiang, Jianbin Liang

Switched reluctance motor (SRM) has a simple geometry and excitation-free rotor construction, which enables more robust operation at high-speed and high-temperature conditions. However, acoustic noise and vibration can be significant concerns in SRMs. The spring-mass models are used to introduce the concepts of natural frequency, damping ratio, forcing frequency, and resonance. As the level of complexity of the structure increases, more complicated mode shapes can appear. Complicated mode shapes can be created based on the mode shapes of simple structures. For SRMs, since the phases conduct in sequence, the forces acting on the stator can be seen as a wave traveling in both time and spatial domains. Before the discussion of analytical expression for surface waves, the data structure of a surface wave needs to be defined. In practice, the oscillation cannot be perpetual because losses will damp the system and, hence, the oscillation of the system will decay.